Pneumo-cystis carinii pneumonia (PCP) is commonly contracted by patients suffering from acquired immuno-deficiency syndrome (AIDS) and also by cancer and organ transplant patients. It has been estimated that some 65% of AIDS patients develop PCP. Amongst such patients the condition is life-threatening.
1,5-Di(4-amidinophenoxy)pentane, which is generically known as pentamidine, has for many years been known for use as a pharmaceutical, in particular for the treatment of the early stages of African trypanosomiasis (`sleeping sickness`). Pentamidine has also been found to be effective in the treatment of PCP infection in AIDS patients when administered by intravenous infusion or intramuscular injection although this treatment is often accompanied by severe side-effects, e.g. hypotension, renal failure and hypoglycaemia. More recently, there has been a report (Abstracts of the Annual Meeting of the American Society of Microbiology 86,14 (1986)) of the prevention of PCP by inhalation of an aerosol spray containing pentamidine or a pharmaceutically acceptable salt thereof. This report, however, relates only to aerosols formed by nebulisation of aqueous solutions.
We have now surprisingly found that pentamidine is effective in the prevention or treatment of PCP when administered by inhalation in powdered form and that formulation of the drug in this way offers certain advantages.